In the 3rd Generation Partnership Project (3GPP), the improvement of a mobile communication system suitable for a machine type communication (MTC) is discussed (see, for example, Non-patent literature 1-3). The MTC is also called a machine-to-machine (M2M) network or a sensor network. When the MTC is implemented in the mobile communication system, a 3GPP communication function (i.e., functions of a mobile station) is typically arranged in a machine (e.g., a vending machine, a gas meter, an electric meter, an automobile, a railway vehicle) or a sensor (e.g., a sensor relating to environment, agriculture, or transportation). The 3GPP defines a mobile station implemented in a machine or a sensor for the MTC as an “MTC device”. The MTC device is connected to a core network of a mobile operator through a cellular radio access network (RAN) and communicates with an MTC user. The MTC user is arranged in an external network and has an MTC application. The MTC application implemented in the MTC user communicates with an MTC application implemented in the MTC device. The MTC user is also called an application server (AS).
As disclosed in Non-patent literature 1, the 3GPP defines three models including a direct model, an indirect model, and a hybrid model to achieve an end-to-end communication on an application layer between the MTC device and the MTC use. In the direct model, the MTC user is directly connected to a mobile operator network, thereby performing a direct user plane (data plane) communication with the MTC device.
Meanwhile, in the indirect model, the MTC user is indirectly connected to the mobile operator network through services provided by a services capability server (SCS), thereby performing an indirect user plane communication with the MTC device and using additional services on a control plane (e.g., triggering to the MTC device). In the indirect model, the SCS communicates with the core network and also communicates with the MTC device through the core network. Further, the SCS provides the MTC user with the user plane interface and the data plane interface (e.g., application program interface (API)). The SCS may be referred to as an MTC server, an M2M service platform, an M2M service server, or an MTC service server. It is expected that the SCS is integrally managed with a core network by a mobile operator, or that the SCS is managed by one or more MTC users instead of the mobile operator. In the latter model, the SCS may be coupled to the MTC user. In other words, the function of the SCS may be integrally arranged with the function of the MTC user.
The hybrid model is a model in which the direct model and the indirect model described above are combined. That is, in the hybrid model, the MTC user directly connects to the operator network for the user plane communication with the MTC device and uses the SCS to use additional services on the control plane.
Specific examples of the MTC application includes smart grids, smart meters, remote control of home appliances, remote control of automobiles, electronic and remote medical services. Further, the cellular RAN is, for example, a UMTS terrestrial radio access network (UTRAN) or an evolved UTRAN (E-UTRAN). The core network is, for example, a general packet radio service (GPRS) packet core or an evolved packet core (EPC).
The 3GPP further has discussed, as disclosed in Non-patent literature 2, an introduction of an “MTC gateway device”. The MTC gateway device has a 3GPP mobile communication function (i.e., functions of a mobile station) and connects with controlled devices (e.g., sensors, radio frequency identification (RFID) tags, and car navigation devices) by means of a personal or local area networking technology. Specific examples of the personal or local area networking technology include IEEE 802.15, ZigBee, Bluetooth, and IEEE 802.11a. Typically, the controlled devices connected to and controlled by the MTC gateway device do not have the 3GPP mobile communication function. Some or all of the controlled devices connected to the MTC gateway device may, however, have the 3GPP mobile communication function (i.e., MTC device). The MTC gateway device is connected to the core network of the mobile operator through a cellular RAN, and communicates with the MTC user (MTC application) directly or through the SCS. In the above indirect model, a protocol stack model is conceivable in which the SCS terminates the connection with the MTC gateway device. In this case, the controlled devices connected to the MTC gateway device communicate with the MTC user (MTC application) through the SCS.
As will be understood from the above description, it can be considered that the MTC gateway device is one of specific examples of a mobile router (or a user equipment (UE) having a tethering function). That is, the MTC gateway device serves as an agent that provides a connection with an external packet network (e.g., a packet data network (PDN)) through a mobile operator network (i.e., a cellular RAN and a core network) for at least one device that is connected to the MTC gateway device by means of the personal or local area networking technology.
Hereinafter, in this specification, a device located behind the MTC gateway device, the mobile router, or the UE having the tethering function (i.e., a device connected to the MTC gateway device, the mobile router, or the UE having the tethering function by means of the personal or local area networking technology) is called a “local device”.
FIGS. 1 to 4 show specific examples of a network architecture regarding the MTC. FIG. 1 shows a specific example of the indirect model. The network architecture shown in FIG. 1 includes an MTC gateway device 91, local devices 92, an SCS 96, and an MTC user (MTC application) 97. The MTC gateway device 91 is connected to the local devices 92 through a personal or local area network 93. The MTC gateway device 91 communicates with the SCS 96 through a mobile operator network (i.e., a cellular RAN 94 and a core network 95). A mobile operator domain 98 indicates a range managed and operated by a mobile operator. In the architecture shown in FIG. 1, the SCS 96 is included in the mobile operator domain 98. As shown in FIG. 2, however, the SCS 96 may be arranged outside of the mobile operator domain 98.
FIG. 3 shows a specific example of the direct model which does not include the SCS 96. In the example shown in FIG. 3, the MTC user 97 performs a direct user plane communication with the core network 95.
FIG. 4 shows a specific example of the hybrid model. In the example shown in FIG. 4, the MTC user 97 is directly connected to the operator network (i.e., core network 95) by a user plane (UP) interface, and is connected to the SCS 96 by a control plane (CP) interface.
The core network 95 shown in FIGS. 1 to 4 has an MTC interworking function (MTC-IWF). The MTC-IWF provides a function which allows the SCS 96 and the control node in the core network to interwork with each other. That is, the MTC-IWF transfers or translates a signaling protocol used for the interface with the SCS to activate the function included in the operator network. The detail of the MTC-IWF is shown, for example, in Non-patent literature 1.